1. Field of the Invention
The present invention relates to a wheel bearing with sensor, more specifically a sensor-equipped wheel support bearing assembly of a kind having a load sensor incorporated in a bearing unit of a vehicle wheel for detecting a load imposed thereon.
2. Description of the Related Art
As a technique for detecting a load imposed on each of vehicle wheels of an automotive vehicle, a sensor-equipped wheel support bearing assembly has been suggested, in which a strain induced in a flange outer diametric surface of an outer ring that serves as a stationary ring of the bearing assembly, is detected. (See, for example, the Patent Document 1 listed below.) The sensor-equipped wheel support bearing assembly of a type, in which a strain gauge is pasted to an outer ring of the bearing assembly for detecting the strain, has also been suggested. (See, for example, the Patent Document 2 listed below.)
In addition, the sensor-equipped wheel support bearing assembly has yet been suggested, in which a sensor unit, made up of a strain generating member and a strain sensor fitted to this strain generating member, is fixed to a stationary ring of the bearing assembly and in which the strain generating member has at least two contact fixing segments adapted to be fixed to the stationary ring and also has a cutout portion, at least one location, between the neighboring contact fixing segments, with the strain sensor arranged in this cutout portion. (See, for example, the Patent Document 3 listed below.)
According to the sensor-equipped wheel support bearing assembly disclosed in the Patent Document 3 referred to above, when a load is imposed on a rotating ring incident to travel of the automotive vehicle, the stationary ring deforms through rolling elements and such deformation in turn brings about a strain in the sensor unit. The strain sensor provided in the sensor unit detects a strain induced in the sensor unit. By determining the relation between the strain and the load by means of a series of experiments and/or simulations in advance, the load acting on a vehicle wheel can be detected from an output of the strain sensor.    [Patent Document 1] JP Laid-open Patent Publication No. 2002-098138    [Patent Document 2] JP Laid-open Patent Publication No. 2003-530565    [Patent Document 3] JP Laid-open Patent Publication No. 2007-057299